CBSE Class 9 Science Improvement in food resources Notes

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IMPRONEMENT IN FOOD RESOURCES 

IMPROVEMENT IN FOOD RESOURCES

IMPROVEMENT IN FOOD RESOURCES

INTRODUCTION

There is a need to increase the production efficiency of crops and livestock because (1) the population is increasing rapidly, and (2) there is no major scope for increasing the area of land under cultivation. Food production must be increased without degrading our environment and disturbing the ecological balance, i.e. sustainable practices are required in agriculture and animal husbandry.

TYPES OF CROPS

• Cereals: wheat, rice, maize, millets and sorghum. They provide carbohydrates for energy requirements.
• Pulses: pea, gram, black gram, green gram, pigeon pea and lentil. They provide proteins.
• Oilseeds: soya bean, groundnut, sesame, castor, mustard, linseed and sunflower. They provide the necessary fats.
• Vegetables, spices and fruits provide vitamins and minerals.

A crop means plants of the same origin grown together in bulk. Every crop requires different climatic conditions, while some crops grow together in one season. The climatic condition, warmth and photo-period for growth and completion are required for different crops. On the basis of the season in which they are grown, crops are divided into two broad types: Kharif crops and Rabi crops.

Rabi crops. Rabi crops or Rabi harvests are the crops in agriculture that are sown in winter or cold season. They are harvested in the spring. Rabi is grown around the month of November to April in our subcontinent. ‘Rabi’ is an Arabic word meaning ‘spring’. The water collected from the rain in this season is the main source of water for these plants. Rabi crops require a greater amount of irrigation. Thus heavy rain may ruin a Kharif crop but is healthy and beneficial for Rabi crops. They are harvested when the monsoon rains have departed. The harvesting may begin by April or May. Major Rabi crops harvested in the subcontinent are wheat, gram, peas, mustard, linseed and barley. Most of the crops are under Rabi season. It is an integral crop in our area.

Kharif crops. Kharif crop refers to the farming, plowing, reaping and harvesting of any household plant sown in the rainy season. They are cultivated for autumn harvest. By the beginning of the first rain in July during the south-west rainy season in monsoon the crops are sown. The season begins on April 16 and ends October 15 in Pakistan, while in India the Kharif season varies from state to state, starting in May and ending latest by January. Popularly in the subcontinent it starts in June and ends by October. The Indian subcontinent is referred to areas covering India, Pakistan, Nepal and Sri Lanka. They are popularly known as monsoon crops. Their growth depends on the quantity and timing of rain: too much or too little rain affects the crop. The harvesting period coincides with the beginning of winter/autumn in the Indian subcontinent. The major Kharif crops harvested in the subcontinent are paddy, soyabean, maize, pigeon pea, cotton, green gram and black gram.

Difference between Kharif and Rabi crops

• Kharif crops are sown between April and May while Rabi crops are sown between September and October.
• Kharif crops are harvested after monsoon rains while Rabi crops are produced after winter.
• Kharif crops are popularly known as monsoon crops while Rabi crops are called winter or spring crops.
• Kharif crops completely rely on the rain, whether it is less or more in quantity, while Rabi crops can deal with whatever water is present for irrigation. Rain has less impact on Rabi crops.
• The major examples of Kharif crops are sunflower, rice, sugar cane, soya bean and tea, while Rabi crops are wheat, barley, pea, gram and mustard.

INTEXT QUESTIONS (PAGE 204)

What do we get from cereals, pulses, fruits and vegetables?

Answer: Cereals provide us with carbohydrates and are a rich source of energy. Pulses give us proteins. Fruits and vegetables are a rich source of vitamins and minerals; a small amount of proteins, carbohydrates and fats is also present in them.

IMPROVING CROP YIELD

The practices involved in farming are divided into three stages: (a) choice of seeds for planting, (b) nurturing of the crop plants, (c) protection of the growing and harvested crops from loss. Hence the major activities for improving crop yields are classified as (i) crop variety improvement, (ii) crop production improvement, (iii) crop protection improvement.

CROP VARIETY IMPROVEMENT

This approach depends on finding a crop variety that can give a good yield. Some of the factors for which variety improvement is done are:

• Higher yield: increasing the productivity per acre.
• Improved quality: quality considerations vary from crop to crop according to requirements.
• Biotic and abiotic resistance: crops should have sufficient resistance to biotic factors (diseases, insects and nematodes) and abiotic stresses (heat, cold, frost etc.).
• Change in maturity duration: the shorter the duration, the more economical the variety.
• Wider adaptability: the variety can be grown in different climatic conditions.
• Desirable agronomic characteristics: tallness and profuse branching for fodder crops; dwarfness for cereals.

Common factors for crop improvement

This can be achieved by two methods: hybridisation and genetically modified crops.

1. Hybridisation. In genetics, hybridisation is the process of combining different varieties or species of organisms which are genetically dissimilar to create a hybrid. It can be inter-varietal, inter-specific or inter-generic.

2. Genetically modified crops. The crop is improved by introducing a gene that provides the desired characteristics.

INTEXT QUESTIONS (PAGE 205)

How do biotic and abiotic factors affect crop production?

Answer: A variety of biotic factors such as pests, nematodes and diseases can reduce the net crop production. A pest causes damage by feeding on crops; for example, the boll weevil is a pest of cotton and reduces its yield. Weeds also reduce crop productivity by competing with the main crop for nutrients, light and space. Similarly, abiotic factors such as salinity and temperature affect crop production. Natural calamities such as droughts and floods are unpredictable, and sometimes destroy the entire crop.

What are the desirable agronomic characteristics for crop improvements?

Answer: Tallness and profuse branching in a fodder crop, and dwarfness in cereals. These desirable agronomic characteristics help in increasing crop productivity.

CROP PRODUCTION MANAGEMENT

It involves the different practices carried out by the farmer to achieve higher standards of crop production. It includes (1) nutrient management, (2) irrigation, (3) cropping patterns.

NUTRIENT MANAGEMENT

The higher yields of crops mainly depend upon inputs like improved seeds, fertilisers and modern techniques of sowing and harvesting. Plants require a number of nutrients for their growth and development. Plants get nutrients from air, water and soil. Sixteen elements are essential for plant growth and reproduction. On the basis of the quantity required, they are classified into macronutrients and micronutrients.

Macronutrients are the elements needed in large quantities for the growth of plants. They are Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Sulphur, Potassium, Calcium, Magnesium and Iron.

Micronutrients are the elements needed by plants in very small quantities. They are Manganese, Copper, Molybdenum, Zinc, Boron and Chlorine.

Deficiency of these nutrients affects physiological processes in plants, including reproduction, growth and susceptibility to disease. To increase the yield, the soil can be enriched by supplying these nutrients in the form of manure and fertilisers.

INTEXT QUESTIONS (PAGE 206)

What are macro-nutrients and why are they called macro-nutrients?

Answer: Macro-nutrients are the nutrients required in relatively large quantities for the growth and development of plants. They are six in number: nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. Since they are required in large quantities, they are known as macro-nutrients.

How do plants get nutrients?

Answer: Plants require sixteen essential nutrients from nature for their growth and development, and all of them are obtained from air, water and soil. Soil is the major source of nutrients: thirteen of these nutrients are available from the soil. The remaining three (carbon, oxygen and hydrogen) are obtained from air and water.

MANURE

Manure is an organic substance prepared by the decomposition of plant and animal wastes. Advantages of manure: it enriches the soil with organic matter and nutrients; it increases soil fertility; it increases the water-holding capacity of the soil; it improves soil texture; it helps to save our environment from the excessive use of fertilisers.

Compost and vermicompost. Composting is the process in which farm waste material (cow dung, domestic waste, sewage waste, etc.) is decomposed in pits. Compost is the aerobically decomposed remnant of organic matter and is rich in nutrients. Vermicomposting uses earthworms to hasten the decomposition of plant and animal refuse.

Green manure. Leguminous plants like sunn-hemp or cluster bean (guar) are grown and then mulched by ploughing them back into the soil. This enriches the soil with nitrogen and phosphorus.

FERTILISERS

Fertilisers are chemicals commercially produced in factories and used as plant nutrients. They supply nitrogen, phosphorus, potassium, etc., and are used to ensure good vegetative growth, giving rise to healthy plants. Advantage: they help in good vegetative growth and produce healthy plants, giving higher yields of crops.

Disadvantages

• Excessive use of fertilisers leads to pollution of water.
• Continuous use of fertilisers decreases soil fertility, because the organic matter of the soil cannot be replenished and the micro-organisms present in the soil are harmed.
• They increase the cost of farming.
• Fertilisers are water-soluble chemicals, so a large part of the fertiliser applied is washed away by excessive irrigation and is not fully absorbed by plants. The excess is washed into ponds, lakes, canals and rivers, resulting in the growth of unwanted plants like water hyacinth and algae. These plants disturb the water bodies and the flow of water. As a result, fishes and other organisms do not get sufficient sunlight and oxygen and die.

Differences between manures and fertilisers

Bio-fertilisers. Fertilisers which are derived from living organisms are called bio-fertilisers. The main sources are bacteria, cyanobacteria and fungi. Bio-fertilisers are renewable and non-polluting sources of plant nutrients and also improve soil condition. Rhizobium and the cyanobacteria Anabaena and Nostoc are some common bio-fertilisers.

INTEXT QUESTIONS (PAGE 207)

Compare the use of manure and fertilisers in maintaining soil fertility.

Answer: Manures increase soil fertility by enriching the soil with organic matter and nutrients, since they are prepared by the decomposition of animal excreta and plant wastes. Fertilisers are mostly inorganic compounds whose excessive use is harmful to the symbiotic micro-organisms living in the soil, and it also reduces soil fertility. Hence fertilisers are considered good for short-term use only.

ORGANIC FARMING

Organic farming is a farming system in which the use of chemicals such as fertilisers, herbicides and pesticides is reduced. It involves the use of: (a) organic manure; (b) recycled farm waste; (c) bio-agents such as cultures of blue-green algae in the preparation of bio-fertilisers; (d) bio-pesticides such as leaves of neem or turmeric for grain storage; (e) healthy cropping patterns such as mixed cropping, intercropping and crop rotation, which also help in controlling the growth of weeds, pests and insects.

IRRIGATION

Irrigation is necessary for crops to get water during their growing season. Sources of irrigation:

• Wells: there are two types of wells, dug wells and tube wells. In a dug well, water is collected from water-bearing strata. Tube wells can tap water from deeper strata. From these wells, water is lifted by pumps for irrigation.
• Canals: usually an elaborate and extensive irrigation system. Canals receive water from one or more reservoirs or from rivers. The main canal is divided into branch canals, which have further distributaries to irrigate the fields.
• River lift systems: in areas where canal flow is insufficient or irregular due to inadequate reservoir release, the lift system is more rational. Water is drawn directly from the rivers to supplement irrigation in areas close to rivers.
• Tanks: small storage reservoirs which intercept and store the run-off of smaller catchment areas.
• Rainwater harvesting and watershed management: building small check dams, which helps in increasing the ground-water level and in reducing soil erosion.

CROPPING PATTERNS

Different ways of growing crops can be used to give maximum benefit.

Mixed cropping. Growing two or more crops simultaneously on the same piece of land is called mixed cropping. When the crops are properly chosen, the products and refuse of one crop help in the growth of the other crop, and vice versa. This improves the fertility of the soil and increases the yield. Mixed cropping is an insurance against crop failure due to abnormal weather and plant pests. Examples: soyabean + pigeon pea, maize + urad dal (black gram), groundnut + sunflower, wheat + chickpea (gram).

Advantages of mixed cropping: no risk of total crop failure; increase in yield; improvement in soil fertility; minimising pest damage.

Intercropping. Intercropping is the agricultural practice of cultivating two or more crops in the same field at the same time in a definite pattern. Row-type intercropping involves the component crops arranged in alternate rows. A variation of this is strip cropping, where multiple rows (a strip) of one crop alternate with multiple rows of another crop. Intercropping also uses the practice of sowing a fast-growing crop with a slow-growing crop, so that the fast-growing crop is harvested before the slow-growing crop starts to mature.

Difference between intercropping and mixed cropping

Selection of crops for mixed cropping and intercropping. Crops are chosen whose nutrient requirements are different, so that the soil nutrients are used to the maximum. Also, their water needs, rooting patterns, etc. should be different. Besides the advantages of mixed cropping, intercropping has these additional advantages: application of pesticides and fertilisers is more convenient because of the well-defined patterns of crops, and harvesting is also easier.

Crop rotation. It is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons, for benefits such as avoiding the build-up of pathogens and pests that often occurs when one species is continuously cropped. Crop rotation also seeks to balance the fertility demands of the various crops to avoid excessive depletion of soil nutrients. A traditional component of crop rotation is the replenishment of nitrogen through the use of green manure (legumes) in sequence with cereals and other crops. Crop rotation can also improve soil structure and fertility by alternating deep-rooted and shallow-rooted plants.

Crop Rotation Plan (cycle): Carrot Family → Corn → Goosefoot Family → Onion Family → Squashes and Melons → Sunflower Family → Brassicas → Legumes → Nightshades → back to Carrot Family.

Advantages: crop rotation avoids a decrease in soil fertility. Growing the same crop repeatedly in the same place eventually depletes the soil of various nutrients. A crop that removes one kind of nutrient from the soil is followed during the next growing season by a dissimilar crop that returns that nutrient to the soil or draws a different ratio of nutrients, for example rice followed by cotton, or cereals followed by legumes. By crop rotation farmers can keep their fields under continuous production, without having to let them lie fallow, and reduce the need for artificial fertilisers, both of which can be expensive. Rotating crops adds nutrients to the soil.

CROP PROTECTION MANAGEMENT

Field crops are infested by a large number of weeds, insect pests and diseases. If weeds and pests are not controlled at the appropriate time, they can damage the crops so much that most of the crop is lost. When the crop is in the field it needs protection against:

• Weeds (e.g. Xanthium, Parthenium): weeds are harmful because they compete with the desired crop for food, space and light. They reduce crop production by taking up the nutrients meant for the crop.
• Insect pests: insect pests attack plants in three ways: (i) they cut the root, stem and leaf; (ii) they suck the cell sap from various parts of the plant; (iii) they bore into the stem and fruits. They thus affect the health of the crop and reduce yields.
• Pathogens: microbes like bacteria, fungi and viruses cause diseases. Spores of these pathogens may be transmitted through soil, water and air.

To control these, herbicides, pesticides and fungicides are used. Weed control methods also include mechanical removal. Preventive methods help in controlling weeds and pests: proper seed-bed preparation, timely sowing of crops, intercropping and crop rotation, use of resistant varieties, and summer ploughing, in which fields are ploughed deep in summer to destroy weeds and pests.

INTEXT QUESTIONS (PAGE 208)

Which of the following conditions will give the most benefits? Why? (a) Farmers use high-quality seeds, do not adopt irrigation and do not use fertilisers. (b) Farmers use ordinary seeds, adopt irrigation and use fertilisers. (c) Farmers use quality seeds, adopt irrigation, use fertilisers and use crop protection measures.

Answer: (c) Farmers using good-quality seeds, adopting irrigation, using fertilisers and using crop protection measures will derive the most benefit.

(i) The use of good-quality seeds increases the total crop production: most of the seeds germinate properly and grow into healthy plants.

(ii) Proper irrigation improves the availability of water to the crops.

(iii) Fertilisers ensure healthy growth and development of plants by providing essential nutrients such as nitrogen, phosphorus and potassium.

(iv) Crop protection measures control weeds, pests and infectious agents. If all these measures are taken by the farmer, the overall production of crops will increase.

STORAGE OF GRAINS

Losses of stored grain occur because of biotic factors (insects, rodents, fungi, mites and bacteria) and abiotic factors (inappropriate moisture and temperature at the place of storage). The negative effects of these factors on grains are: degradation in quality, loss in weight, poor germinability, discolouration of the produce, and, as a result, poor marketability.

Prevention and control methods used before grains are stored: cleaning of the produce before storage; drying of the produce first in sunlight and then in shade to reduce its moisture content; fumigation using chemicals (fumigants) to kill pests.

INTEXT QUESTIONS (PAGE 209)

Why should preventive measures and biological control methods be preferred for protecting crops?

Answer: Preventive measures and biological control methods should be preferred because excessive use of chemicals leads to environmental problems, and these chemicals are also poisonous for plants and animals. Preventive measures include proper soil and seed preparation, timely sowing of seeds, intercropping and mixed cropping, and the use of resistant varieties of crops. Biological control methods include the use of bio-pesticides, which are less toxic to the environment. An example of a bio-pesticide is Bacillus thuringiensis, an insect pathogen that kills a wide range of insect larvae. Therefore both are considered eco-friendly methods of crop protection.

What factors may be responsible for losses of grains during storage?

Answer: Various biotic factors such as insects, rodents, mites, fungi and bacteria, and various abiotic factors such as inappropriate moisture and temperature, are responsible for losses of grains during storage. These factors act on stored grains and result in degradation, poor germinability, discolouration, etc.

ANIMAL HUSBANDRY

The branch of agriculture which deals with the feeding, shelter, health and breeding of domestic animals such as cattle, pigs, horses and fowls is called animal husbandry. Its various elements are: (1) proper feeding of animals, (2) provision of clean drinking water, (3) proper shelter, (4) prevention and cure of animal diseases, (5) proper breeding of animals.

Advantages of animal husbandry. As animal husbandry is the scientific management of farm animals, it serves many uses: it helps in enhancing milk production, egg production, meat production and fish production, and in the proper management of agricultural wastes.

CATTLE FARMING

Cattle farming is the practice of rearing cattle by providing facilities for raising livestock. Livestock includes cows, buffaloes, sheep, goats, pigs, etc. Cattle farming is carried out to raise cows and buffaloes. The two major species of Indian cattle are Bos indicus (cows) and Bos bubalis (buffaloes).

Milch animals and draught animals. On the basis of their utility, cattle are classified into two types. Milch (dairy) animals produce milk; the males of this type are not useful for work on the farm. Draught animals are used for agricultural work like tilling, irrigation and carting; the cows of this category are poor milk-yielders.

Management practices for cattle farming include cleaning, sheltering and feeding:

1. Cleaning involves periodic washing to get rid of dirt and loose hair.
2. Shelter facilities include well-ventilated roofed sheds which protect cattle from rain, cold and sun.
3. Feeding of cattle includes a supply of uncontaminated and balanced diet. Animal feed is of two types: roughage and concentrates. Roughage has a high fibre content (fodder grasses, silage and legumes). Concentrate feed is a mixture of cereals, seeds and oilseed cake rich in protein; it is easily digestible and helps the animal to increase its body weight.
4. Cattle should be protected from diseases. Diseases in cattle are caused by external and internal parasites. External parasites live on the skin and cause skin diseases. Internal parasites affect the stomach and intestines. Preventive measures: proper disposal of dead animals and animal wastes; shelters should be clean, dry and well ventilated; periodic visits of a veterinary physician; hygienic management of animals and animal products.
5. Infectious diseases are caused by pathogens like bacteria, viruses and fungi. Sheds should be cleaned and disinfected regularly, and vaccination against the various diseases should be provided to the farm animals.
6. Milk production depends on the duration of the lactation period, the period following the birth of a calf during which milk is produced by the animal. The lactation period can be enhanced by administering certain hormonal injections.
7. Cross-breeding is done between foreign and local breeds of animals to produce animals with desired qualities. Example: a foreign breed like Jersey cow, with a long lactation period, is crossed with a local breed like Red Sindhi, with high resistance to disease, to obtain offspring having both a long lactation period and high disease resistance.

Advantages of cross-breeding: to increase milk production; to increase resistance against diseases; to develop varieties with a longer lactation period; to rely on a smaller amount of quality feed.

INTEXT QUESTIONS (PAGE 210)

Which method is commonly used for improving cattle breeds and why?

Answer: Cross-breeding is commonly used for improving cattle breeds.

Cross-breeding between two good varieties of cattle produces a new, improved variety. For example, the cross between foreign breeds such as Jersey and Brown Swiss (having long lactation periods) and Indian breeds such as Red Sindhi and Sahiwal (having excellent resistance to diseases) produces a new variety having the qualities of both breeds. The purpose is to increase the production of milk and of draught labour for agricultural work.

Dairy animals (females) are used for obtaining milk and draught animals (males) are engaged in agricultural fields for labour work such as carting, irrigation and tilling.

POULTRY FARMING

Poultry farming is the practice of raising fowl for egg production and chicken meat. Fowls (layers) are used for producing eggs and broilers are used for producing meat. Cross-breeding is common in poultry to develop new varieties with desirable traits; for example, the Indian breed Aseel is crossed with the foreign breed Leghorn. The desirable traits include: number and quality of chicks; dwarf broiler parents for commercial chick production; summer adaptation capacity (tolerance to high temperature); low maintenance requirements; and reduction in the size of the egg-laying bird, with the ability to use more fibrous, cheaper diets formulated from agricultural by-products.

Management practices for poultry farming: maintaining optimum temperature; providing hygienic housing conditions; providing a protein-rich diet with high levels of vitamins A and K; and preventing and controlling pests and diseases.

INTEXT QUESTIONS (PAGE 211)

Discuss the implications of the following statement: “It is interesting to note that poultry is India’s most efficient converter of low-fibre food stuff (which is unfit for human consumption) into highly nutritious animal protein food.”

Answer: Poultry in India efficiently converts low-fibre food stuff, which humans cannot use, into highly nutritious animal protein food such as eggs and chicken. In poultry farming, domestic fowls are raised for eggs and meat. For this, the fowls are given animal feeds in the form of roughage, which mainly consists of fibres. Thus, by feeding animals a fibre-rich diet, the poultry gives highly nutritious food in the form of eggs and chicken.

What management practices are common in dairy and poultry farming?

Answer: Common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning; (ii) basic hygienic conditions such as clean water and nutritious food; (iii) keeping the animals in a spacious, airy and well-ventilated place; (iv) prevention and cure of diseases at the right time.

What are the differences between broilers and layers and in their management?

Answer: Layers are meant for egg production, whereas broilers are meant for poultry meat. The nutritional, environmental and housing conditions required by broilers are different from those required by egg layers. For proper growth a broiler requires vitamin-rich supplements, especially vitamins A and K. Their diet includes protein-rich food and enough fat. Broilers also require extra care and maintenance to increase their survival rate, compared to egg layers.

FISH FARMING

Fish farming is also called aquaculture: the culture of fish for commercial purposes. Fish is a cheap source of animal protein.

Types of fishery. (a) Fin fishery and shell fishery. Fish production involves fin fishery and shell fishery. Two main species of finned true fish are catla and rohu; shellfish are prawns and molluscs.

(b) Capture fishery and culture fishery. Fish are obtained by capture fishing as an economic source of meat. Capture fishing is capturing fish from sea water or fresh water. Culture fishing involves culturing fish in small enclosures such as ponds and tanks. Capture fishing is classified into marine fishery and inland fishery depending upon the resources used for fishing. Fish farming can be done in rice fields, where both grain and fish can be harvested from the farm.

Since the feeding habits of fish differ from species to species, many varieties can be reared on the same farm. Composite fish farming is the rearing of different varieties of fish in the same area. For example, composite fish farming includes catla (surface feeder), rohu (feeds in the middle zone of a pond), mrigal and common carp (bottom feeders) and grass carp (feeds on weeds). These species can co-exist in a single pond and thus increase the yield of fish from the pond.

(c) Marine fishery and inland fishery. Mariculture is the culture of fish in marine water. Marine fishery involves fishing in salt-water regions. Examples of marine fish: pomfret, tuna and mackerel. Fish are captured by locating large schools of fish in the open sea with the help of satellites and echo-sounders. Marine fish of high economic value are farmed in seawater, and shellfish such as prawns, mussels and oysters are also farmed in seawater. Oysters are cultivated for their pearls.

Distinguishing features between capture fishery, mariculture and aquaculture

Inland fisheries involve fresh-water canals, ponds, reservoirs and rivers from which fish are captured. Estuaries are the regions where fresh water mixes with sea water; they are rich sources of fish.

Fish farming faces the problem of lack of quality seed or eggs. Fish are therefore bred in ponds by hormonal stimulation: they are injected with hormones that stimulate the production of eggs (seed). This ensures the supply of pure fish seed in the desired quantities.

APICULTURE

The scientific method of rearing honeybees for honey and wax is called apiculture or bee-keeping. Beehives are enclosed structures in which honeybees live and raise their young. The practice of maintaining honeybee colonies in beehives is called bee-keeping. Apiaries or bee farms are established for the commercial production of honey. Bee-keeping is a cheap and popular agricultural enterprise. Honey produced in the beehives is used in food and medicines; its taste and quality depend upon the flowers the bees visit for nectar collection. Wax obtained from the hives is used in ointments, polishes, etc.

Types of bees. There are three types of bees in a colony:

1. Queen: the only fertile female in the hive; its function is to lay eggs.
2. Drones: fertile male bees; their function is to mate with the queen bee and fertilise the eggs.
3. Workers: sterile females. They take care of the queen and the young bees, collect nectar, build honeycombs and protect the beehive.

Honeybee varieties. Indigenous varieties: Apis indica (common Indian honeybee), Apis dorsata (rock bee), Apis florea (little bee). Exotic varieties: Apis mellifera (Italian bee), Apis adamsoni (South African bee).

Economic importance. Honeybees are used in the production of honey and beeswax.

Uses of honey

1. Honey is an energy-rich food; for example, 1 kg of honey provides about 3200 calories of energy.
2. Honey contains sugars, minerals, vitamins, enzymes and pollen.
3. Honey is an antiseptic and contains formic acid as a preservative.
4. Honey is a blood purifier and a cure for cough, cold, sore throat, and ulcers of the tongue, stomach and intestine.
5. Honey helps in building up the haemoglobin content of the blood.
6. Honey is used in the preparation of bread, cakes and biscuits.

Beeswax is used in the manufacture of cosmetics, lubricants, cold creams, shaving creams, polishes, candles, ointments and medical preparations.

INTEXT QUESTIONS (PAGE 213)

How are fish obtained?

Answer: Fish can be obtained in two ways: (i) capture fishing, the process of obtaining fish from natural resources; (ii) culture fishery, the practice of farming fish. Farming can be done in both fresh-water ecosystems (river water, pond water) and marine ecosystems.

What are the advantages of composite fish culture?

Answer: Composite fish culture increases the yield of fish. In it, five or six different species are grown together in a single fish pond. Fishes with different food habits are chosen so that they do not compete for food among themselves. This ensures complete utilisation of the food resources in the pond. As a result, the survival rate of the fish and their yield increase.

What are the desirable characters of bee varieties suitable for honey production?

Answer: Bee varieties suitable for honey production should: (i) yield a high quantity of honey; (ii) not sting much; (iii) stay in the beehive for long durations; (iv) breed very well.

What is pasturage and how is it related to honey production?

Answer: Pasturage is the availability of flowers from which bees collect nectar and pollen. It is related to honey production because it determines the taste and quantity of the honey.

EXERCISE QUESTIONS

Explain any one method of crop production which ensures high yield.

Answer: Crop rotation is one method of crop production that ensures a high yield. It is the method of growing two or more varieties of crops on the same land in sequential seasons. A crop uses some particular nutrients in larger quantities from the soil. If the same crop is grown in subsequent seasons, those nutrients get depleted. Therefore crops with different nutrient requirements are rotated. For example, legumes, which have nitrogen-fixing bacteria in their root nodules, supply the soil with nitrogen, so legumes are rotated with nitrogen-requiring cereals such as wheat and maize. This method reduces the need for fertilisers and increases the overall yield.

Why are manure and fertilisers used in fields?

Answer: Manure and fertilisers are used in fields to enrich the soil with the required nutrients. Manure enriches the soil with organic matter and nutrients, which improves the fertility and structure of the soil. Fertilisers ensure healthy growth and development of plants; they are a good source of nitrogen, phosphorus and potassium. To get an optimum yield, a balanced combination of manure and fertilisers is recommended.

What are the advantages of inter-cropping and crop rotation?

Answer: Both inter-cropping and crop rotation play an important role in increasing the yield of crops. Inter-cropping helps in preventing pests and diseases from spreading throughout the field and increases soil fertility. Crop rotation prevents soil depletion and increases soil fertility. Both methods reduce the need for fertilisers, help in controlling weeds, and control the growth of pathogens and pests in crops.

What is genetic manipulation? How is it useful in agricultural practices?

Answer: Genetic manipulation is a process in which the gene for a particular character is introduced into the chromosome of a cell. When the gene for a particular character is introduced into a plant cell, a transgenic plant is produced, which shows the character governed by the newly introduced gene.

For example, if the gene responsible for large fruit size is introduced into a wild plant that produces small fruits, the plant becomes transgenic and starts producing larger fruits. Similarly, genes for higher yield, disease resistance, etc. can be introduced into any desired plant.

Gene manipulation thus helps in improving crop varieties. It ensures food security, gives insect-resistant crops and improves the quality and yield of crops.

How do storage grain losses occur?

Answer: Various biotic and abiotic factors act on stored grains and result in degradation, poor germinability, discolouration, etc. Biotic factors include insects and other pests, which cause direct damage by feeding on the seeds; they also deteriorate and contaminate the grain, making it unfit for consumption. Abiotic factors such as temperature, light, moisture, etc. also affect the seed. They decrease the germinating ability of the seeds and make them unfit for future use by farmers. Unpredictable occurrence of natural calamities such as droughts and floods also causes destruction of crops.

How do good animal husbandry practices benefit farmers?

Answer: Cattle farming is one of the methods of animal husbandry that is most beneficial for farmers. Using this method, better breeds of draught animals can be produced. Such draught animals are engaged in agricultural fields for labour work such as carting, irrigation, tilling, etc. In general, good animal husbandry practices (proper feeding, clean water, shelter, disease control and breeding) increase the production of milk, eggs, meat and fish and give better breeds of animals. For example, cattle farming gives better breeds of milch animals and of draught animals, which are engaged in agricultural fields for labour such as carting, irrigation and tilling.

What are the benefits of cattle farming?

Answer: (i) Good quality and quantity of milk can be produced. (ii) Draught animals can be produced for agricultural work. (iii) New varieties that are resistant to diseases can be produced by crossing two varieties with the desired traits.

For increasing production, what is common in poultry, fisheries and bee-keeping?

Answer: The common factor is proper management techniques. Regular cleaning of the farms is of utmost importance. Maintenance of temperature and prevention and cure of diseases are also required to increase the number of animals and the production.

How do you differentiate between capture fishing, mariculture and aquaculture?

Answer: Capture fishing is the method of obtaining fish from natural resources. Mariculture is the culture of marine fishes for commercial use. Aquaculture involves the production of aquatic animals of high economic value, such as prawns, lobsters, fishes, crabs, etc.

b) Rabi crops.

Main seasonal plants are divided into two broad categories. The crops that grow in monsoon period is called Kharif crops which is around June to October. The crops that are harvested in winter period are called Rabi crops which are around November to April.

Please click the link below to download CBSE Class 9 Science Improvement in food resources Notes.